Benzodiazepine receptor (BzR) ligands are structurally different compounds, which bind to the γ-aminobutyric acidA (GABAA)/BzR complex. They display a broad pharmacological effect stretching from the full agonistic agents exhibiting anxiolytic, anticonvulsant, sedative-hypnotic and myorelaxant activities to the inverse agonistic agents, which displays anxiogenic, somnolytic and convulsant activities. In between antagonistic agents that elicit no pharmacological effect are present.
The (GABAA)/BzR complex is a membrane-bound pentameric ligand gated chloride ion channel assembled of at least 21 subunits from eight different classes (α1-6, β1-4, γ1-4, δ, ε, π, θ, and ρ1-3).i,ii The large number of possible assemblies is somewhat reduced as a completely operational (GABAA)/BzR consist of at least one α, one β and one γ subunit, and the most abundant receptors in vivo contain two α, two β and one γ subunits. Moreover the α1βxγ2, α2βxγ2, α3βxγ2 and α5βxγ2 subtype assemblies are regard as the major benzodiazepine binding receptors, the benzodiazepine binding-site being located at the interface between the α and the γ subunit. Recent studies with transgenic mice and subtype selective compounds clearly suggest that receptors with different subtype composition are associated with different physiological effect e.g. α1-containing receptors mediate sedation and anterograde amnesia, α2-, and/or α3-containing receptors are involved in anxiolytic activity, and α5-containing receptors might be associated with cognition and memory.iii,iv 
A broad spectrum of BzR binding non-benzodiazepines has been presented and among the most potent are compounds belonging to the following classes cyclopyrrolones, 2-arylpyrazoloquinolines, β-carbolines, pyridodiindoles, triazoloqunioxalines, pyrimidin-5(6H)-ones, and quinolines. Structure-activity relationship of 136 different ligands from ten structurally different classes of compounds was applied in the creation of a comprehensive pharmacophore model for the BZ receptor. The model was developed under the hypothesis that BZ receptor agonists, inverse agonists, and antagonists all share the same binding pocket.